Typically, wind turbine towers carry the nacelle and the rotor of a wind turbine in order to allow for the desired rotation of the rotor and to raise the rotor into a position as far as possible from the ground as wind speeds typically increase with the distance to the ground.
A wind turbine tower may be constructed according to several different principles, e.g. as tubular steel towers, lattice towers or even concrete towers.
Most large wind turbines are delivered with tubular steel towers manufactured in sections of 20-30 meters with flanges at both ends, and bolted together on the site. The towers are typically conical in order to increase strength and save materials at the same time.
The steel towers typically comprise an interior with platforms, ladders, illumination means, power cables, lifts, etc. The components are welded to the inner surface of the steel tower section, or directly attached to the fittings, which have been welded and/or bolted to the tower.
One of several problems associated with the above-described wind turbine towers is that the welding or bolting of especially the interior tower components such as ladders, cables, etc., weaken the tower structure.
In some cases it is possible to compensate for this problem by taking relatively costly precautions.